The present invention relates to a pair of spectacles to be worn by a golfer to facilitate the alignment of a golf ball with a target.
In a pair of spectacles known from U.S. Pat. No. 3,264,002, in order to achieve this object, the transparent optical means carried by the spectacle frame have an opaque horizontal line, that is, a line parallel to a tangent of the upper edges of the frame, so that a player wearing the spectacles sees a hazy, dark, guide line between the ball and the target which, in this case, is represented by the hole in a green.
In a similar pair of spectacles known from U.S. Pat. No. 4,991,849, the transparent optical means are tinted like a sun filter and carry a clear horizontal line which may be constituted by grooves cut in the surfaces of the lenses or by a thin, untinted strip of the optical means, produced by the application of a mask in that region during the tinting of the optical means. The spectacles described in this patent also have a device for adjusting the distance between the bridge which carries the lenses and the rest of the frame in order to adjust the distance between the clear line and the golfer's eyes.
A first disadvantage of these known solutions lies in the fact that, in practice, the player cannot focus on a thin, clear or dark line carried by the optical means of the spectacles and thus see it clearly (as, after all, is admitted in the description of the U.S. Pat. No. 3,264,002) and this causes discomfort to the person wearing the spectacles.
A further disadvantage of these known solutions lies in the fact that, particularly when the golfer is executing a "drive", he has to arrange himself parallel to an imaginary line linking the ball and the target; as he moves his arms before making the stroke, however, a right-handed player naturally tends to turn his head to the right as he focuses his eyes on the ball so that, as he effects the stroke, the attitude of his body diverges from the imaginary line by an angle which, in practice, varies between 5.degree. and 15.degree..
Since, in the spectacles known from the two patents cited above, the lines carried by the optical means for facilitating the alignment of the ball and the target are horizontal, the lines follow the movement of the user's head and hence cannot give him a correct indication of the alignment of the ball and the target.